Neural organization of eye movements in depth

描述(申请人提供)：通常需要双眼旋转角度不同的错位动眼反应。海林等神经支配定律指出，有两组动眼神经指令。共轭命令将眼睛在相同的方向上以相同的量旋转，类似于弯折的眼睛对。聚焦命令通过在相反方向上以相同的量旋转眼睛来控制眼睛之间的角度。任何不共轭的眼睛旋转都可以通过适当的共轭和收敛命令来获得。最近的证据表明，一些错位反应可能是由独立的左眼和右眼不对称命令驱动的，可能直接到达汇聚通路外的运动神经元。这些假定的单眼信号在功能上有意义吗？我们将通过估计由融合系统直接在神经元水平上编码的分离命令的百分比来解决这个问题。如果海林定律是正确的，收敛系统必须解释整个错位反应，而与刺激的类型或产生它的动眼系统无关。这些估计将在以下过程中完成：1)静止目标之间的深度注视的自愿转移；2)对深度移动的小目标的自愿平滑跟踪；3)超短潜伏期反射性视觉稳定反应；以及4)线性前庭-眼睛反应。单单位记录的神经目标将是中脑中与融合相关的细胞。双眼的水平、垂直和扭转眼球运动将与这些细胞的神经活动一起被记录下来。高场解剖和功能磁共振成像将有助于定位这些区域。复视会使视觉功能严重退化。至少有4%的美国人受到长期双眼对准缺陷的影响，如斜视和弱视。了解分离指令是如何产生并传递到眼外肌的，对于制定影响双眼对齐的眼球运动障碍的正确临床治疗至关重要，无论是作为眼球运动缺陷的来源的诊断，还是在选择适当的手术或光学干预时。对这些机制的神经基础的了解将是理解眼球运动适应过程的关键工具，该过程帮助患者重新校准他/她的眼动命令，以恢复或至少部分改善人们所知较少的双眼性。

DESCRIPTION (provided by applicant): Disconjugate oculomotor responses, where the two eyes rotate by different amounts, are often needed. Hering's law of equal innervation states that there are two groups of oculomotor commands. Conjugate commands rotate the eyes in the same amount in the same direction similarly to a yoked pair. Vergence commands control the angle between the eyes by rotating the eyes in same amount in the opposite direction. Any disconjugate eye rotation can be obtained by appropriate conjugate and vergence commands. Recent evidence shows that some disconjugate responses may be driven by independent left- and right-eye asymmetric commands, perhaps directly reaching the motor neurons outside the vergence pathway. Are these putative monocular signals functionally significant? We will address this question by estimating the percentage of disconjugate command encoded by the vergence system directly at the neuronal level. If Hering's law is correct, the vergence system must account for the entire disconjugate response, independently of the type of stimulus or the oculomotor system in which it was generated. These estimates will be done during: 1) voluntary transfers of gaze in depth between stationary targets; 2) voluntary smooth tracking of small objects moving in depth; 3) ultra-short latency reflexive visual stabilization responses; and 4) linear vestibulo-ocular responses. Neural targets for the single-unit recordings will be the vergence-related cells in midbrain. Binocular horizontal, vertical, and torsional eye movements will be recorded together with the neural activity of these cells. High-field anatomical and functional MRI will help localize these areas. Visual function is severely degraded by double vision. At least 4% of the US population is affected by long- term deficits in binocular alignment, such as strabismus and amblyopia. The understanding of how disconjugate commands are generated and delivered to the extraocular muscles is of critical importance in developing a correct clinical management of oculomotor disorders affecting binocular alignment, both as diagnosis of the source of the oculomotor deficit and the selection of the proper surgical or optical intervention. Knowledge of the neural substrate of these mechanisms will be a crucial tool in the understanding of the oculomotor adaptive processes that help a patient recalibrate his/her eye movement commands to regain, or at least partially improve, binocularity, which are poorly understood.